- existing infrastructure (roads) isn't going anywhere (no need to build anything)
- reduced traffic congestion (autonomous vehicles can better react/drive)
- improved supply chains (autonomous trucks) (can work 0-24)
just to name a few off top of my head
I think that this is a sunk-cost fallacy. Sure, you would need to build infrastructure for trains, but after that trains are now reasonably automated, can carry cargo, and do other things with the exception of stopping at the exact destination you wanted to (in other words, it requires predetermined stops which people outside the US shrugs and just walk or bike the last feet). Also, they're proven to work: even China (which previously didn't have trains to its far-flung places) and they've done what you've expect. I think that the sole reason that anyone wants to invest in automated (non-train) driving is because trains are boring while AI is oh-so-shiny.
But with the levels of investment in cars and roads, we could have mini trains on reduced tracks (think stuff like mine tracks) going almost anywhere, probably for a fraction of maintaining our road infrastructure and cars.
https://en.wikipedia.org/wiki/Interstate_Highway_System
https://en.wikipedia.org/wiki/National_Highway_System_(Unite...
This, and leaving from the exact starting point you want to, at the exact time you want to, without out-of-the-way intermediate stops that you don't want, without switching lines. I can also easily move a table, couch, 2 shopping carts full of groceries, etc.
It's not an insignificant difference in convenience
You don't need full autonomy to mostly fix this, but the fixes are politically untenable (currently). The cars should be speed-governed, they should be speed-limit aware -- the car should routinely be overriding the desire of the driver. No, you can't go into the bike lane to get around traffic. No, you can't make the split-second decision to swerve around a car braking in front of you. No, you can't operate the vehicle at 100 mph in a residential zone. No, you can't go that fast right now; it's raining way too hard, doofus. No, you can't operate your vehicle onto a scheduled parade route.
You don't need full autonomy to create cars that prevent a significant percentage of driver -- to put it charitably -- errors. These are fairly straightforward problems. The opposition is political.
We will find ourselves in the same position with speed regulators, etc. Once some country does it, the reduction in lives lost will be impossible to ignore.
(although the risk is clearly that vehicles will transition into subscription services that cost many thousands of dollars a year and price them all out)